HOST GUEST SENSORY SYSTEMS FOR DETECTING ORGANIC-COMPOUNDS BY PYRENE EXCIMER FLUORESCENCE

The pyrene excimer emission from the association dimers of pyrene-appended γ-cyclodextrlns, γ-PI and γ-P2, was used to detect a variety of organic compounds in a 10% dimethyl sulfoxide aqueous solution. When the association dimers, in which two pyrene moieties form an excimer, were converted into 1:1 host-guest complexes upon guest addition, the intensity of excimer emission decreased while that of the monomer Increased. The sensitivities of γ-PI and γ P2. as evaluated by the decrease of the excimer emission intensity caused by the guest addition, depended on the polarity, shape, and the size of the guest molecules, and were particularly high to some steroidal compounds such as chenodeoxycholic acid, ursodeoxycholic acid, and lithocholic acid. The position and the number of hydroxyl groups of some steroids were suggested to be the factors that govern the sensitivities. Many ketosteroids and amines decreased both monomer and excimer emission Intensities due to their quenching effects. The binding constants of γ-P1 for cholic acid derivatives were always larger than those of γ-P2, but the sensitivity of γ-PI for each guest was slightly smaller than that of γ-P2, reflecting the extremely high stability of the association dimer of γ-PI Alkaloids including kinine and strykinine were hardly detected with these systems. We have demonstrated the first example of host-guest sensory systems, where organic compounds Including biologically important substances can be detected by pyrene excimer fluorescence with significant sensitivities and selectivities. © 1990, American Chemical Society. All rights reserved.